The present invention relates to data processing apparatus including a cordless keyboard used for office computers, personal computers and terminal equipment in banks.
In the office computers, personal computers and terminal equipment in banks, the devices are grouped depending upon their functions into keyboards for operation, CRT displays for monitoring, and control units for effecting electronic processing from the standpoint of improving operability and effectively utilizing the desk. On the desk are arranged the keyboard with which the operation can be carried out at all times and the CRT display, and the control unit that requires no operation is installed under or by the desk. Cables run among them hindering the operation, occupying space and impairing the appearance. Therefore, attempts have been made to eliminate the wires by using optical signals instead of using cables as disclosed in, for example, U.S. Pat. No. 4,313,227.
According to the conventional apparatus, however, reliability is not necessarily maintained sufficiently in transmitting the signals between the keyboard and the control unit without using cord. Furthermore, under the environment in which the office computers or terminal equipment in a bank are operated simultaneously such as in an office or at the windows of the bank, light affects one another among the apparatuses from which erroneous operation may result.
With the keyboard having no wire, furthermore, the circuitry in the keyboard must be operated by a power source such as cells. When used for business in offices and in banks, the keyboard must be operated for about eight hours a day, and the cells must be renewed or must be recharged almost everyday.